1. Field of the Invention
The present invention relates to a digital information recording-reproducing apparatus, or more in particular to a digital information recording-reproducing apparatus having a time-base restoration function.
2. Description of the Related Art
The Journal of the Institute of Television Engineers of Japan, Vol. 47, No. 4, April 1993, pp. 494-499, describes a system conceived to transmit audio or video software through a radio wave or a cable to be recorded in each home.
In this conventional system, however, the rate at which software information is transmitted, recorded and reproduced is fixed. Especially, no measure is taken to shorten the recording time.
Also, the problem of the above-mentioned conventional system is that the sale or rent which may be made of audio or video software requires management of information on customers, number of days rented, etc.
One such system may be interactive, in which the user requests the video software he wants from the transmitting end, and the software supplier transmits the desired software. In such a case, however, it takes a predetermined length of time before the wanted digital information signal is actually transmitted from the time the particular video software is requested. More specifically, the transmitting end is required to prepare the video data to be transmitted or to stand by until a transmission channel becomes available. This leads to the problem that the user cannot determine the time to start his VTR.
A first object of the invention is to obviate the above-mentioned problems and to provide a digital information recording-reproducing apparatus having the functions of shortening the recording time and restoring the signal on time base.
A second object of the invention is to obviate the above-mentioned problems and to provide a digital information recording-reproducing apparatus capable of easily managing information on customers, number of days rented, etc.
A third object of the invention is to obviate the above-mentioned problems and to provide a digital information recording-reproducing apparatus simple to operate, in which recording errors can be minimized.
In order to achieve the first object, according to the invention, there is provided a digital information recording-reproducing apparatus in which software information is transmitted by being reduced to 1/n temporally, the received software reduced to 1/n temporally is recorded in magnetic tape at a predetermined rate, and the recorded signal is reproduced at the rate 1/n the recording rate.
In order to achieve the second object, according to the invention, there is provided a digital information recording-reproducing apparatus in which control codes such as the user number and the recording date are additionally recorded in the recording signal so that the information on customers, number of days rented, etc. are managed based on the added information at the time of reproduction.
According to a first method for achieving the third object of the invention, there is provided a digital information recording-reproducing apparatus comprising a control signal generator at the transmitting end for controlling the operating conditions of recording-reproducing means (VTR), wherein an output signal of the control signal generator is transmitted together with a digital information signal through transmission means before recording, and a control signal detector at the receiving end is connected with the receiver and produces an output signal thereby to control the VTR in recording mode.
According to a second method for achieving the third object of the invention, there is provided a digital information recording-reproducing apparatus comprising a control signal generator at the transmitting end for controlling the operating conditions of the VTR, second transmission means for transmitting an output signal of the control signal generator, and a control signal detector at the receiving end, wherein an output signal of the control signal generator is transmitted through the second transmission means before starting the recording, the VTR is controlled in recording mode by the output signal of the control signal detector, and the digital information signal transmitted through the first transmission means is recorded by the VTR.
According to a third method for achieving the third object of the invention, there is provided a digital information recording-reproducing apparatus wherein the magnetic tape is divided into a number a  of recording areas (a: integer of 1 or more) each assigned to one video software.
The recording time can be shortened to 1/n by recording the software information temporally compressed to 1/n.
At the time of reproduction, the signal is reproduced at the rate 1/n the recording rate, and therefore the time axis is expanded by n times to reproduce the original software information before temporal compression.
At the time of reproduction, the control information including the user number and recording date are read. In the case where the user number is different, however, no reproducing operation is performed. In the case of software rental, on the other hand, no reproducing operation is performed after the lapse of a predetermined time from the recording. By so doing, information on customers, the number of days rented, etc. can be managed appropriately.
According to the first method, the control signal for controlling the VTR in recording mode is transmitted through the same transmission channel of radio wave or cable before the digital information signal of the video software to be transmitted. A demodulator at the receiving end, once it has received the control signal, immediately sets the VTR in recording mode.
According to the second method, the control signal for controlling the VTR in recording mode is transmitted through a second transmission channel such as the telephone line different from the transmission channel for transmitting the digital information signal before the digital information signal of the video software to be transmitted. A second demodulator at the receiving end, once it has received this control signal, immediately or after the lapse of a predetermined time, sets the VTR in recording mode.
According to the third method, the magnetic tape is divided beforehand (preformatted) into a plurality of recording areas, each of which is assigned to a video software for sequentially recording the video data from the tape starting section. In the process, the recording information on the video data that has been recorded in each area is recorded in the header or tail section of the particular area, and according to the contents of the recording information, the next area to be recorded is automatically selected.